gen_compile_commands: fix invalid escape sequence warning

With python 3.12, '\#' results in this warning
SyntaxWarning: invalid escape sequence '\#'

Signed-off-by: Andrew Ballance <andrewjballance@gmail.com>
Reviewed-by: Justin Stitt <justinstitt@google.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

gen_compile_commands.py: fix path resolve with symlinks in it

When a path contains relative symbolic links, os.path.abspath() might
not follow the symlinks and instead return the absolute path with just
the relative paths resolved, resulting in an incorrect path.

1. Say "drivers/hdf/" has some symlinks:

# ls -l drivers/hdf/
total 364
drwxrwxr-x 2 ... 4096 ... evdev
lrwxrwxrwx 1 ... 44 ... framework -> ../../../../../../drivers/hdf_core/framework
-rw-rw-r-- 1 ... 359010 ... hdf_macro_test.h
lrwxrwxrwx 1 ... 55 ... inner_api -> ../../../../../../drivers/hdf_core/interfaces/inner_api
lrwxrwxrwx 1 ... 53 ... khdf -> ../../../../../../drivers/hdf_core/adapter/khdf/linux
-rw-r--r-- 1 ... 74 ... Makefile
drwxrwxr-x 3 ... 4096 ... wifi

2. One .cmd file records that:

# head -1 ./framework/core/manager/src/.devmgr_service.o.cmd
cmd_drivers/hdf/khdf/manager/../../../../framework/core/manager/src/devmgr_service.o := ... \
/path/to/src/drivers/hdf/khdf/manager/../../../../framework/core/manager/src/devmgr_service.c

3. os.path.abspath returns "/path/to/src/framework/core/manager/src/devmgr_service.c", not correct:

# ./scripts/clang-tools/gen_compile_commands.py
INFO: Could not add line from ./framework/core/manager/src/.devmgr_service.o.cmd: File \
/path/to/src/framework/core/manager/src/devmgr_service.c not found

Use os.path.realpath(), which resolves the symlinks and normalizes the paths correctly.

# cat compile_commands.json
...
{
"command": ...
"directory": ...
"file": "/path/to/bla/drivers/hdf_core/framework/core/manager/src/devmgr_service.c"
},
...

Also fix it in parse_arguments().

Signed-off-by: Jialu Xu <xujialu@vimux.org>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

gen_compile_commands: Sort output compile commands by file name

Make the output more stable and deterministic.

Signed-off-by: Ian Rogers <irogers@google.com>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Cc: Ravi Bangoria <ravi.bangoria@amd.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Yang Jihong <yangjihong1@huawei.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: llvm@lists.linux.dev
Cc: Ming Wang <wangming01@loongson.cn>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Tom Rix <trix@redhat.com>
Cc: bpf@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-perf-users@vger.kernel.org
Link: https://lore.kernel.org/r/20231009183920.200859-3-irogers@google.com
Signed-off-by: Namhyung Kim <namhyung@kernel.org>

gen_compile_commands: Allow the line prefix to still be cmd_

Builds in tools still use the cmd_ prefix in .cmd files, so don't
require the saved part. Name the groups in the line pattern match so
that changing the regular expression is more robust and works with the
addition of a new match group.

Signed-off-by: Ian Rogers <irogers@google.com>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Cc: Ravi Bangoria <ravi.bangoria@amd.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Yang Jihong <yangjihong1@huawei.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: llvm@lists.linux.dev
Cc: Ming Wang <wangming01@loongson.cn>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Tom Rix <trix@redhat.com>
Cc: bpf@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-perf-users@vger.kernel.org
Link: https://lore.kernel.org/r/20231009183920.200859-2-irogers@google.com
Signed-off-by: Namhyung Kim <namhyung@kernel.org>

gen_compile_commands: add assembly files to compilation database

Like C source files, tooling can find it useful to have the assembly
source file compilation recorded.

The .S extension appears to used across all architectures.

Signed-off-by: Benjamin Gray <bgray@linux.ibm.com>
Reviewed-by: Fangrui Song <maskray@google.com>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

kbuild: rename cmd_$@ to savedcmd_$@ in *.cmd files

The cmd-check macro compares $(cmd_$@) and $(cmd_$1), but a pitfall is
that you cannot use cmd_<target> as the variable name for the command.

For example, the following code will not work in the top Makefile
or ./Kbuild.

quiet_cmd_foo = GEN $@
cmd_foo = touch $@

targets += foo
foo: FORCE
$(call if_changed,foo)

In this case, both $@ and $1 are expanded to 'foo', so $(cmd_check)
is always empty.

We do not need to use the same prefix for cmd_$@ and cmd_$1.
Rename the former to savedcmd_$@.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nicolas Schier <nicolas@fjasle.eu>

kbuild: change module.order to list *.o instead of *.ko

scripts/Makefile.build replaces the suffix .o with .ko, then
scripts/Makefile.modpost calls the sed command to change .ko back
to the original .o suffix.

Instead of converting the suffixes back-and-forth, store the .o paths
in modules.order, and replace it with .ko in 'make modules_install'.

This avoids the unneeded sed command.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Luis Chamberlain <mcgrof@kernel.org>

kbuild: use obj-y instead extra-y for objects placed at the head

The objects placed at the head of vmlinux need special treatments:

- arch/$(SRCARCH)/Makefile adds them to head-y in order to place
them before other archives in the linker command line.

- arch/$(SRCARCH)/kernel/Makefile adds them to extra-y instead of
obj-y to avoid them going into built-in.a.

This commit gets rid of the latter.

Create vmlinux.a to collect all the objects that are unconditionally
linked to vmlinux. The objects listed in head-y are moved to the head
of vmlinux.a by using 'ar m'.

With this, arch/$(SRCARCH)/kernel/Makefile can consistently use obj-y
for builtin objects.

There is no *.o that is directly linked to vmlinux. Drop unneeded code
in scripts/clang-tools/gen_compile_commands.py.

$(AR) mPi needs 'T' to workaround the llvm-ar bug. The fix was suggested
by Nathan Chancellor [1].

[1]: https://lore.kernel.org/llvm/YyjjT5gQ2hGMH0ni@dev-arch.thelio-3990X/

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Nicolas Schier <nicolas@fjasle.eu>

gen_compile_commands: handle multiple lines per .mod file

scripts/clang-tools/gen_compile_commands.py incorrectly assumes that
each .mod file only contains one line. That assumption was correct when
the script was originally created, but commit 9413e7640564 ("kbuild:
split the second line of *.mod into *.usyms") changed the .mod file
format so that there is one entry per line, and potentially many lines.

The problem can be reproduced by using Kbuild to generate
compile_commands.json, like this:

make CC=clang compile_commands.json

In many cases, the problem might be overlooked because many subsystems
only have one line anyway. However, in some subsystems (Nouveau, with
762 entries, is a notable example) it results in skipping most of the
subsystem.

Fix this by fully processing each .mod file.

Fixes: 9413e7640564 ("kbuild: split the second line of *.mod into *.usyms")
Signed-off-by: John Hubbard <jhubbard@nvidia.com>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

gen_compile_commands: fix missing 'sys' package

We need to import the 'sys' package since the script has called
sys.exit() method.

Fixes: 6ad7cbc01527 ("Makefile: Add clang-tidy and static analyzer support to makefile")
Signed-off-by: Kortan <kortanzh@gmail.com>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

gen_compile_commands: extract compiler command from a series of commands

The current gen_compile_commands.py assumes that objects are always
built by a single command.

It makes sense to support cases where objects are built by a series of
commands:

cmd_<object> := <command1> ; <command2>

One use-case is that <command1> is a compiler command, and <command2>
an objtool command.

It allows *.cmd files to contain an objtool command so that any change
in it triggers object rebuilds.

If ; appears after the C source file, take the first command.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Kees Cook <keescook@chromium.org>

gen_compile_commands: prune some directories

If directories are passed to gen_compile_commands.py, os.walk() traverses
all the subdirectories to search for .cmd files, but we know some of them
are not worth traversing.

Use the 'topdown' parameter of os.walk to prune them.

Documentation about the 'topdown' option of os.walk:
When topdown is True, the caller can modify the dirnames list
in-place (perhaps using del or slice assignment), and walk() will
only recurse into the subdirectories whose names remain in dirnames;
this can be used to prune the search, impose a specific order of
visiting, or even to inform walk() about directories the caller
creates or renames before it resumes walk() again. Modifying
dirnames when topdown is False has no effect on the behavior of
the walk, because in bottom-up mode the directories in dirnames
are generated before dirpath itself is generated.

This commit prunes four directories, .git, Documentation, include, and
tools.

The first three do not contain any C files, so skipping them makes this
script work slightly faster. My main motivation is the last one, tools/
directory.

Commit 6ca4c6d25949 ("gen_compile_commands: do not support .cmd files
under tools/ directory") stopped supporting the tools/ directory.
The current code no longer picks up .cmd files from the tools/
directory.

If you run:

./scripts/clang-tools/gen_compile_commands.py --log_level=INFO

then, you will see several "File ... not found" log messages.

This is expected, and I do not want to support the tools/ directory.
However, without an explicit comment "do not support tools/", somebody
might try to get it back. Clarify this.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Acked-by: Nathan Chancellor <nathan@kernel.org>

scripts/clang-tools: switch explicitly to Python 3

For the same reason as commit 51839e29cb59 ("scripts: switch explicitly
to Python 3"), switch some more scripts, which I tested and confirmed
working on Python 3.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Acked-by: Nathan Chancellor <nathan@kernel.org>

Makefile: Add clang-tidy and static analyzer support to makefile

This patch adds clang-tidy and the clang static-analyzer as make
targets. The goal of this patch is to make static analysis tools
usable and extendable by any developer or researcher who is familiar
with basic c++.

The current static analysis tools require intimate knowledge of the
internal workings of the static analysis. Clang-tidy and the clang
static analyzers expose an easy to use api and allow users unfamiliar
with clang to write new checks with relative ease.

===Clang-tidy===

Clang-tidy is an easily extendable 'linter' that runs on the AST.
Clang-tidy checks are easy to write and understand. A check consists of
two parts, a matcher and a checker. The matcher is created using a
domain specific language that acts on the AST
(https://clang.llvm.org/docs/LibASTMatchersReference.html). When AST
nodes are found by the matcher a callback is made to the checker. The
checker can then execute additional checks and issue warnings.

Here is an example clang-tidy check to report functions that have calls
to local_irq_disable without calls to local_irq_enable and vice-versa.
Functions flagged with __attribute((annotation("ignore_irq_balancing")))
are ignored for analysis. (https://reviews.llvm.org/D65828)

===Clang static analyzer===

The clang static analyzer is a more powerful static analysis tool that
uses symbolic execution to find bugs. Currently there is a check that
looks for potential security bugs from invalid uses of kmalloc and
kfree. There are several more general purpose checks that are useful for
the kernel.

The clang static analyzer is well documented and designed to be
extensible.
(https://clang-analyzer.llvm.org/checker_dev_manual.html)
(https://github.com/haoNoQ/clang-analyzer-guide/releases/download/v0.1/clang-analyzer-guide-v0.1.pdf)

The main draw of the clang tools is how accessible they are. The clang
documentation is very nice and these tools are built specifically to be
easily extendable by any developer. They provide an accessible method of
bug-finding and research to people who are not overly familiar with the
kernel codebase.

Signed-off-by: Nathan Huckleberry <nhuck@google.com>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Tested-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>